Background/Rational: The overall goal of this project is to develop a community resource of immuno-multiple reaction monitoring (immuno-MRM) assays that will allow the detection and quantitation of human proteins. In this demonstration stage of the development of immuno-MRM assays, our goal will be to complete the production and distribution of a subset of assays for a widely studied cellular process or pathway (for example, receptor tyrosine kinase (RTK)/RAS signaling pathway). The goal of this demonstration project would be to prepare assays that would detect and quantitate the majority of proteins that act in this pathway, all of the mutant alleles of this pathway that might be found in a test sample, and key phosphorylation sites that help regulate the activity of this pathway. These reagents and assay protocols will be placed in the public domain and made available worldwide to non-profit organizations without restriction and at cost. A current goal is show that such assays can be developed efficiently and within a reasonable budget, that the resulting assays are useful to the community, and that they can be widely distributed. We anticipate that successful completion of this demonstration project will show that the process can be expanded to allow the development of tests for virtually any or all proteins of interest.